Joaquim de Mariz Junior was born on the 28th January 1847, in Coimbra (Portugal).
He was the son of Joaquim de Mariz and of Maria José Pinto. He studied in Coimbra. He graduated from
the Faculty of Medicine of the University
of Coimbra, and gained
distinctions in various subjects of the course. He practiced medicine until 1879, when he applied for Assistant botanist
to teach Botany at the University
of Coimbra, a position he
held until his death.

He was a committed scientist, always
carrying out his duties zealously. He excelled
as a botanical taxonomist. He studied exhaustively the Portuguese phanerogamic
flora, studying more than 200 species, sent to him by the members of the
Broterian Society. He did a magnificent work of identifying and classifying
botanical samples. He revised the massive herbarium of the Botanical Gardens of
Coimbra; the names of the vast majority of the species existing in this herbarium were written by him. He compiled
many studies in descriptive botanic about many families: Papilionaceae, Cruciferaceae, Ranunculaceae, Cariofilaceae,
Crassulaceae, Geraniaceae, Asteraceae or Compositae, Umbelíferaceae,
Polygonaceae. Chenopodiaceous, Valerianaceae, Dipsacaceae, Ambrosiaceae,
Primulaceae, Gencianaceae, Solanaceae, Convolvulaceae, Cuscutaceae,
Caprifoliaceae, Ericaceae, Monotropeae, Vaciniaceae and Verbaceae. This was
a magnificent work and of crucial importance to the study of the Portuguese
flora.

His expertise as botanical taxonomist made
him very popular amongst other great botanists of his time. He co-operated in
the preparation of the Flora of Portugal of Gonçalo Sampaio and António Xavier
Pereira Coutinho, clearing many doubts and identifying a lot of material for
these two authors.

He produced many botanical studies, which
include a vast number of plant catalogues, which were published in the Bulletin
of the Broterian Society, a society of which he was a member and untiring collaborator.

He frequently collected plants, during
which he collected many samples for the herbarium. During these visits to the
field, he discovered many new species, for the country and for science and gave
an important contribution to draft the geo-botanical map of Portugal.

He led a long scientific expedition to Trás-os-Montes, especially in the
district of Bragança, studying in great depth de “transmontana” flora. In this task, e carried out vast collections
of plants and the methodical analysis. The catalogues of the plants collected
and the register of the analysis made are found in the Bulletin of the
Broterian Society.

Joaquim de Mariz had a talent for art,
drawing and engraving. He did the
pictures of the Botanical gardens such as the «a Estufa» (the Hothouse), of 1867.